1. Technical Field
The present invention relates to composite coating systems and methods for the manufacture and reconstruction of condensate pans, floors, internal structures, and other related structures of Heating Ventilation and Air Conditioning (HVAC) or Heating Ventilation Air Conditioning and Refrigeration (HVACR) units. The composite coating systems and methods are especially suitable for commercial HVAC and HVACR units. The present invention also relates to composite coating systems and methods for other surfaces and applications. The present invention can, for example, reduce and/or prevent corrosion and/or fire hazards and/or smoke hazards.
2. Background
Metallic and cementicious condensate pan substrates, internal support structures, and flooring within a Heating Ventilation and Air Conditioning (HVAC) or Heating Ventilation Air Conditioning and Refrigeration (HVACR) unit are subjected to cyclic temperature, humidity and water exposure whereby corrosion often takes place. The condensate pans are of particular interest. They are often composed of steel, galvanized steel, stainless steel, concrete and the like. The condensate pans facilitate the collection and drainage of water as a direct result of the condenser coil functions within the main system unit. Water or moisture in the air-stream condenses on the coils because of temperature differential or humidification apparatus within the unit. The water drips from the coils into the collection pan where it is intended to drain into the waste water system. Internal structures (walls, ceilings, mechanical equipment supports, and flooring within the unit, for example) are all subject to corrosion and often need refurbishment.
Several commercial products are currently available for coating of condensate pans and other surfaces. Example for such products include the Foster Drip Pan Coating 40-60 (Foster Products, Palatine, Ill.), Pancrete (Controlled Release Technologies, Inc., Clearwater Fla.), MAGNA-Coat (MAGNA-Coat Industrial Coatings, Georgetown, Tex.), and SAFE Corrosion Control & Marine Systems (SAFE Encasement Systems, Las Vagas, N.V.). Existing products fall short in many respects.
A multitude of problems can occur during the lifecycle of these structures and systems within the HVAC or HVACR system environment, particularly with respect to condensate pans. For example, during pan installations or during routine maintenance the pan geometry and drainage slope are often compromised by being walked upon. Corrosion, equipment vibration, and normal wear and tear are also problematic to the overall integrity of the pan. In many cases, older pans were not originally designed with sloping features from the manufacturer.
The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 62 1998, “Ventilation for Acceptable Indoor Air Quality” now requires drain pans to be designed for self-drainage or sloped to allow the water to properly drain. Uneven pan surfaces, whether originally designed as such or through other means, cause water to pond and become stagnant and may not satisfy ASHRAE standards.
In addition to corrosion from standing or ponding water, mold, fungus, slime and various other microbes can grow and flourish, causing the pan and drain system to become biologically unsafe. In addition to the biohazards created, the organisms eventually clog the drain system. The plugged drainage system and faulty pan designs add to the propensity of condensate water to pond, thereby causing further corrosion and microbial growth.
Over time, the accumulation of water promotes pan corrosion, eventually leading to leakage. Leakage infiltrates building structures and systems causing further issues with building components, electrical systems and equipment. Leaking water also furthers the proliferation of mold and microbial growth.
Past HVAC design practices have included pans made from sandwich composites of plastic foam (polyurethane, expanded polystyrene, etc.) encapsulated in sheet steel. These foam materials have been used as a water barrier in addition to providing insulation. Pan corrosion can and often does eat away the top layer of steel undesirably exposing the foam plastic to the environmental air-handling stream. Furthermore, the foam plastic material is extremely flammable and does not meet the NFPA 255 flammability requirements within the National Fire Code requirements of NFPA 90A. The composite coating system of the present invention has also been designed to encapsulate this foam, bringing it back into regulatory compliance.
In addition to the above issues, a significant problem that the industry has not yet overcome with typical pan refurbishment coatings is compliance with the National Fire Code. Pan refurbishments currently marketed in the form of coatings (or any combustible material used in condensate pan applications) should comply with the National Fire Code, promulgated by the National Fire Protection Association (NFPA). NFPA Standard 90A “Standard for the Installation of Air-Conditioning and Ventilating Systems”, 2002 edition specifically addresses this application.
The NFPA 90A code states that any combustible products within the environmental air handling stream must meet a maximum Flame Spread Index of 25 and a maximum Smoke Developed Index of 50 per NFPA 255 “Standard Method of Test of Surface Burning Characteristics of Building Materials”, 2002 Edition. The code also goes on to say that combustible products used in the HVAC air-stream must meet the flame and smoke performance requirements and do so without evidence of continued progressive combustion in the thickness and form in which they are intended to be used. Of course, it is undesirable to allow distribution of smoke from an HVAC system to a building. Embodiments of the composite coating system of the present invention can fully comply with these regulations. No other currently marketed products, including all of the known competitive coating products, meet this regulatory code requirement.
Condensation pans, floors and other components within commercial HVAC units can be quite large. Some condensate pans are on the order of 100 square feet or more. These large air-handling systems are prevalent in virtually all commercial buildings. Most of the 4.6 million commercial buildings in the United States have large HVAC units; some high-rise buildings can have 20 or more such units. Over time, due to stagnant water, pans that collect condensate water often corrode, leak and provide an ideal environment for the growth of mold, fungi and other biohazard organisms effecting Indoor Air Quality (IAQ). Legionellosis, Legionnaires' Disease (LD) and Pontiac Fever have been linked to IAQ issues.
The problem is often discovered when water leaking from condensate pans travel throughout the building, particularly to the floors below. Typical situations include hospital HVAC pans leaking on to very expensive and critical equipment such as a Magnetic Resonance Imaging (MRI) machines and other equipment. This leads to equipment corrosion, contamination and electrical shock safety issues, equipment downtime and the like.
As mentioned above, another problem associated with standing water within the pan is the growth of various biocontaminants like fungi, bacteria and other microorganisms. The HVAC system in a building delivers conditioned air to the occupants throughout the building for warmth, cooling, comfort, and breathing air necessary for the operation of the building. The delivery and spreading of biocontaminants in a building, such as through the HVAC system, is undesirable. Microbes need four basic ingredients to thrive: (1) organic nutrients or “food”; (2) moisture in the form of standing water or humid air; (3) a surface on which to grow; and (4) darkness. Therefore, if the HVAC air conveyance systems are kept clean and dry, the potential for microbial contamination within a building can be significantly reduced.
Various problems with HVAC systems are of particular concern within the healthcare, pharmaceutical, food manufacturing and educational industries and institutions.